This invention relates to an abrasive tool, and in particular, a tool with two abrasive sides bonded to a core. This invention also relates to a support structure, and in particular, a support structure with two sheets bonded to a core.
Support structures used in various industrial applications are designed to maximize rigidity and stiffness and to minimize weight of materials, production costs and difficulty of manufacture and assembly. Such a support structure may be, e.g., an abrasive tool used to sharpen, grind, hone, lap or debur a work piece or substrate of hard material, e.g., a knife. Such an abrasive tool may have a surface coated with abrasive grains such as diamond particles. An abrasive tool having an abrasive surface with depressions, e.g., an interrupted cut pattern, is known to be effective for chip clearing when applied to various work pieces. Abrasive tools must be rigid and durable for many commercial and industrial applications.
In general, in one aspect, the invention features an abrasive tool including a first perforated sheet having a front surface and a back surface, and a second perforated sheet having a front surface and a back surface. A first layer of abrasive grains is bonded to the front surface of the first perforated sheet, and a second layer of abrasive grains is bonded to the front surface of the second perforated sheet. A core, which is made of a first material, includes a first wall having an inner surface and an outer surface, a second wall having an inner surface and an outer surface, and a plurality of walls each connected to both the inner surface of the first wall and the inner surface of the second wall to space the first wall from the second wall and to form a plurality of hollow spaces within the core. The back surface of the first perforated sheet is disposed adjacent to the outer surface of the first wall and the back surface of the second perforated sheet is disposed adjacent to the outer surface of the second wall. The core is bonded to the first perforated sheet and the second perforated sheet by forming the core between the first perforated sheet and the second perforated sheet.
Implementations of the invention may include one or more of the following features. The core may be formed between the first perforated sheet and the second perforated sheet by injection molding, casting or laminating. The first material may include a plastic material, which may be a glass filled polycarbonate composite. The first material may include resin, epoxy or a cementitious material.
The first and second perforated sheets may have perforations that are counterbored or bevelled such that a portion of each of the perforations adjacent to the front surfaces of the sheets is wider than a portion of each of the perforations that is adjacent to the back surfaces of the sheets. The first material may be disposed within the counterbored or bevelled perforations to anchor the perforated sheets to the core.
The first and second perforated sheets may have perforations arranged to form an interrupted cut pattern. The first and second perforated sheets may have perforations in a portion less than the entirety of the sheets.
The first and second layers of abrasive grains may be bonded to the front surfaces of the first and second perforated sheets respectively by a plating material. The first and second layers of abrasive grains may have different degrees of abrasiveness.
The tool may be a file or a whetstone. The plurality of walls may form the plurality of hollow spaces along an edge of the abrasive tool.
In general, in another aspect, the invention features a first sheet having a front surface, a back surface and a first anchoring member, and a second sheet having a front surface, a back surface and a second anchoring member. A first layer of abrasive grains is bonded to the front surface of the first sheet, and a second layer of abrasive grains is bonded to the front surface of the second sheet. A core, which is made of a first material, includes a first wall having an inner surface and an outer surface, a second wall having an inner surface and an outer surface, and a plurality of walls each connected to both the inner surface of the first wall and the inner surface of the second wall to space the first wall from the second wall and to form a plurality of hollow spaces within the core. The back surface of the first perforated sheet is disposed adjacent to the outer surface of the first wall and the back surface of the second perforated sheet is disposed adjacent to the outer surface of the second wall. The core is bonded to the first anchoring member of the first sheet and the second anchoring member of the second sheet by forming the core between the first sheet and the second sheet.
Implementations of the invention may also include one or more of the following features. The anchoring members may include studs, expanded metal sheets, or perforated sheets in which the perforations have a portion adjacent to the front surface of the perforated sheet that is wider than a portion of the perforation that is adjacent to the back surface of the perforated sheet.
An advantage of the present invention is the ease and simplicity of using injection molding to form the core for the support structure or abrasive tool.
Another advantage of the present invention is the strength, durability, and dimensional stability of the support structure or abrasive tool, which allows for selection from a wide range of materials.
Another advantage of the present invention is the high strength-to-weight ratios of the composite material used to form the support structure or abrasive tool compared to any of the construction materials singularly.
Another advantage of the present invention is the economies of scale that can be achieved by fabricating a single tool with multiple abrasive surfaces.
A further advantage is the versatility of the support structure or abrasive tool, which may have varying shapes, uses and different grades of abrasiveness for each of the surfaces.
Other features and advantages of the invention will become apparent from the following detailed description, and from the claims.